Organosilicone coating compositions

Abstract

Coating compositions in accordance with the invention are usefully coated on substrates, such as plastic lenses, and cured. The cured coatings provide excellent abrasion resistance and good adherence and weathering properties. The coating compositions comprise an organic solvent and a mixture of at least two components derived by partial hydrolysis from precursor organosilicone compounds. The precursor compounds include a plurality of alkoxy groups, and the at least two components are partially hydrolyzed by greater than 40% of a stoichiometric amount of water required to hydrolyze the alkoxy groups. A first component of the two components is in an imine, aminal or enamine form, which extends working life of the coating compositions.

We claim: 
     
       1. A coating composition, useful for forming mar resistant coatings, comprising: an organic solvent; and,   a mixture of at least two components, said mixture being dissolved in said organic solvent, a first component of said at least two components being derived from an aminoalkylalkoxysilane precursor as a partially hydrolyzed, nitrogen containing imine, aminal, enamine, or mixture thereof, a second component of said at least two components being an epoxy containing, partially hydrolyzed compound derived by partial hydrolysis from an epoxyalkylalkoxysilane precursor, said aminoalkylalkoxysilane precursor and said epoxyalkylalkoxysilane precursor both having a plurality of alkoxy groups, said first and second components being partially hydrolyzed by greater than 40% of a stoichiometric amount of water required to hydrolyze said plurality of alkoxy groups.   
     
     
       2. The coating composition as in claim 1 wherein: said first component is a condensate being selected from the group consisting of hydrocarbylidene amino hydrocarbyl alkoxy silane, hydrocarbenamine hydrocarbyl alkoxy silane, hydrocarbylidene amino hydrocarbenamine alkoxy silane, N,N-hydrocarbyl alkyl silane aminal, and mixtures thereof.   
     
     
       3. The coating composition as in claim 1 wherein: said first component is decomposable, and has a determined total of nitrogen active hydrogens upon decomposition, and said first and second components are admixed with a ratio of said determined total of nitrogen active hydrogens per epoxy group of said second component of about 0.5 to about 3.   
     
     
       4. The coating composition as in claim 1 wherein said first component decomposes to a partially hydrolyzed, aminoalkylalkoxysilane having primary or secondary amino groups, the decomposition being sufficiently complete to permit a reaction between epoxy groups of said second component and amino groups of the decomposed first component, but being sufficiently slow to delay the reaction. 
     
     
       5. The composition as in claim 1 wherein: said first and second components are partially hydrolyzed by from about 60% to about 80% of the stoichiometric amount of water required to hydrolyze said plurality of alkoxy groups.   
     
     
       6. The coating composition as in claim 5 wherein: said mixture is about 20 to about 50 wt. % of said coating composition.   
     
     
       7. The composition as in claim 4 wherein said first component is derived from said aminoalkylalkoxysilane precursor, or a partial hydrosylate thereof, and at least a stoichiometric amont, with respect to said aminoalkylalkoxysilane precursor, of a carbonyl containing compound. 
     
     
       8. The coating composition as in claim 7 wherein: said carbonyl containing compound is a ketone, an aldehyde, or mixtures thereof.   
     
     
       9. The coating composition as in claim 4 wherein: said mixture includes a third component, said third component reactable with said amino groups of the decomposed first component or the epoxy groups of the second component.   
     
     
       10. A coating composition, useful for providing thermoset, mar resistant coatings and having an extended working life, formed by the steps comprising: (a) partially hydrolyzing alkoxy groups of an aminoalkylalkoxysilane;   (b) forming a partially hydrolyzed condensate between the partially hydrolyzed aminoalkylalkoxysilane of step (a) and an excess of a carbonyl containing compound;   (c) partially hydrolyzing alkoxy groups of an epoxyalkylalkoxysilane; and,   (d) admixing the partially hydrolyzed condensate of step (a) with the partially hydrolyzed epoxyalkylalkoxysilane of step (c), the partially hydrolyzed condensate and the partially hydrolyzed epoxyalkylalkoxysilane being partially hydrolyzed by from about 60% to about 80% of a stoichiometric amount of water required for complete hydrolysis.   
     
     
       11. The coating composition as in claim 10 further comprising: adding a monomeric or polymeric component to the partially hydrolyzed condensate, the monomeric or polymeric component being present in the admixture of step (d).   
     
     
       12. The coating composition as in claim 10 further comprising: adjusting the admixture of step (d) with sufficient organic solvent to provide from about 20 wt. % to about 50 wt. % of the admixture in said coating composition.   
     
     
       13. The coating composition as in claim 12 wherein: the adjusting provides from about 20 wt. % to about 35 wt. % of the admixture in said coating composition.   
     
     
       14. A method for increasing the working life of silane based coating compositions comprising (a) partially hydrolyzing alkoxy groups of an aminoalkylalkoxysilane;   (b) forming a partially hydrolyzed imine condensate from the partially hydrolyzed aminoalkylalkoxysilane of step (a) and an excess of a carbonyl compound;   (c) partially hydrolyzing alkoxy groups of an epoxy alkylalkoxysilane;   (d) admixing the partially hydrolyzed imine condensate of step (b) with the partially hydrolyzed epoxyalkylalkoxysilane of step (c);   (e) then regenerating partially hydrolyzed aminoalkylalkoxysilane from the partially hydrolyzed imine condensate to thereby react the regenerated partially hydrolyzed aminoalkylalkoxy silane with the epoxy alkylalkoxysilane.   
     
     
       15. The method of claim 14 wherein all of said reactions are carried out in a non-aqueous solvent. 
     
     
       16. The method of claim 14 wherein the partially hydrolyzed aminoalkylalkoxysilane is regenerated from the partially hydrolyzed imino condensate by the application of heat to the composition mixture. 
     
     
       17. The method of claim 14 wherein the partially hydrolyzed aminoalkylalkoxysilane is regenerated by the addition of moisture to the composition mixture at step (e). 
     
     
       18. The method of claim 14 wherein the aminoalkylalkoxysilane is hydrolyzed to greater than 40 percent of the total hydrolyzable alkoxy groups present on said silane. 
     
     
       19. The method of claim 18 wherein the aminoalkylalkoxysilane is hydrolyzed to from about 60 percent to about 80 percent of the total hydrolyzable alkoxy groups. 
     
     
       20. The method of claim 14 wherein the epoxyalkylalkoxysilane is hydrolyzed to greater than 40 percent of the total hydrolyzable alkoxy groups present on said silane. 
     
     
       21. The method of claim 20 wherein the epoxyalkylalkoxysilane is hydrolyzed to from about 60 percent to about 80 percent. 
     
     
       22. A method for producing highly mar and scratch resistant coatings based on the condensation products of aminoalkylalkoxysilanes and epoxyalkylalkoxysilanes comprising (a) dissolving aminoalkylalkoxysilane in an organic solvent;   (b) adding sufficient water to hydrolyze greater than 40 percent of the alkoxy groups of said aminoalkylalkoxysilane;   (c) reacting the hydrolyzed aminoalkylalkoxysilane with a carbonyl compound to form hydrolyzed iminoalkylalkoxysilane;   (d) dissolving epoxyalkylalkoxysilane in an organic solvent;   (e) adding sufficient water to hydrolyze greater than 40 percent of the alkoxy groups of said epoxyalkylalkoxysilane;   (f) combining said hydrolyzed iminoalkylalkoxysilane solution with said hydrolyzed epoxyalkylalkoxysilane solutions;   (g) regenerating aminoalkylalkoxysilane from said iminoalkylalkoxysilane by adding further moisture to the combined solutions;   (h) reacting said regenerated aminoalkylalkoxysilane with the epoxyalkylalkoxysilane; and then   (i) coating the reacted aminoalkylalkoxysilane and epoxyalkylalkoxysilane onto a substrate; and   (j) evaporating the organic solvent to yield an adherant mar and scratch resistant coating on said substrate.